Airseal dampers have been proposed which comprise a circular opening with a circular domed disk provided to open and close the opening and thereby control gaseous flow therethrough. In a closed position the disk, which has a diameter greater than that of the opening, lies over the opening parallel to the plane thereof with the outer periphery of the disk in sealing engagement with a forward surface of the frame peripherally about the opening.
In opening the damper, the disk is moved, firstly, forwardly away from the opening while maintaining the disk substantially parallel to the plane of the opening. Once the disk has been moved a desired distance forwardly of the frame, the disk is then pivoted approximately about a diameter of the disk until the disk assumes a position substantially normal to the plane of the opening. Advantageously, portions of the disk will, in the fully open position, extend rearwardly through the opening. The disk may thus be moved forwardly of the opening only so far as is required to permit the disk to pivot to a position normal to the opening without contacting the opening.
Previous mechanisms to move the disk between open and closed positions suffer a number of disadvantages. Such mechanisms have been unduly complex and required an excessive number of machined parts increasing their expense, ease of manufacture and weight. Previous mechanisms have not provided for satisfactory alignment of moving elements with the result of only partial engagement between bearing surfaces and uneven wearing of bearing surfaces. Previous mechanisms have been rather large with the disadvantage of providing excessive restriction of air-flow when positioned in the air flow path. Their large size is a disadvantage during installation.
Accordingly, it is an object of the present invention to at least partially overcome the disadvantages of the previous mechanisms by providing a novel caming assembly to move the disk between its open and closed positions which assembly comprises carriage means coupled to support means for controlled movement of the carriage means with respect to the support means due to the interaction of camming pins fixed on the carriage means and slidable in closed slots in the support means.
In one of its aspects the present invention provides a damping assembly have a circular opening in a planar frame surface and a complementary circular disk marginally greater than the opening to regulate flow of gas through the opening,
the disk assuming a first closed position in which the disk lies in the plane of the opening on a first forward side of the opening with the periphery of the disk in sealing engagement with the frame surface surrounding the opening, PA0 the disk movable forwardly away from the opening to an intermediate position in which it may be rotated substantially about a diameter of the disk toward a fully open position with the plane of the disk substantially normal to the plane of the opening and with a portion of the disk extending rearwardly through the opening, PA0 a camming assembly to move the disk between its open and closed positions, the camming assembly comprising: PA0 support means comprising two substantially identical parallel support plates coupled to the frame surface and extending normal to the plane of the opening rearwardly from approximately the center of the rear of the disk when fully closed, PA0 carriage means comprising two substantially identical parallel carriage plates fixedly coupled to the center of the rear of the disk and extending rearwardly normal to the plane of the opening when the disk is fully closed, PA0 a side surface of each carriage plate in close sliding juxtaposition to a side surface of one of the support plates to guide the carriage plates on movement rearward and forwardly and maintain the carriage plates parallel with the support plates, PA0 each support plate having therethrough a first camming slot and a first bore, PA0 each carriage plate having therethrough a second camming slot and a second bore, PA0 a first axle member extending between the support plates through the first bores and into the second slots of the carriage plates to be received in slidable camming engagement in each of the second slots, PA0 a second axle member extending between the support plates through the first slots of the support plates and into the second bores, the second axle member received in slidable camming engagement in each of the first slots, PA0 the second slots located forward of the second bores, PA0 each second slot being substantially straight and extending forwardly from a rear end to a forward end, PA0 the first bores located proximate the forward end of the support plates, PA0 each first slot having a rear end rearward of the first bore, the first slot extending forwardly from its rear end as a first substantially straight slot portion having a length and configuration similar to that of the second slots, PA0 the first slot portion merging at its forward extent into a second substantially arcuate slot portion, the center of which describes an arc of a circle centered on the axis of the first bore and having a radius equal to the distance between the center of the rear end of the second slot and the axis of the second bore, PA0 the second slot portion extending from the forward extent of the first slot portion forwardly and to one side of the first bore to terminate at the forward end substantially far forward as the first bore, PA0 actuating means providing reciprocal forward extension and rearward retraction of a piston rod and coupled to the support means rearward of the first slot for pivotting about an axis parallel to the first and second axle member and normal to the direction the piston rod is extendable and retractable, PA0 the piston rod extending between the support plate and coupled at a free forward end to the second axle member,
wherein:
(a) with the piston rod fully rearwardly retracted the disk is in a fully closed position with the carriage means drawn as far rearwardly as possible with the second axle member proximate the rear ends of the first slots and with the first axle member proximate the front ends of the second slots, and PA1 (b) upon forward extension of the piston rod from a fully closed position, the piston rod moves the carriage means forwardly substantially in a direction normal to the plane of the opening with the carriage means being guided by the first axle member sliding in the second slots to the rear end thereof at the same time as the second axle member slides in the first slot portions to the forward extent thereof, and upon further forward extension of the piston rod with the first axle member received in the rear end of the second slots, the second axle member slides in the second arcuate slot portions to the forward end thereof thereby pivoting the carriage means about the first axle member so as to pivot the disk to a plane substantially normal to the plane of the opening.